卤化物
钙钛矿(结构)
材料科学
空位缺陷
光伏系统
维数之咒
激子
带隙
光电子学
平面的
钛
太阳能电池
纳米技术
结晶学
无机化学
化学
计算机科学
凝聚态物理
物理
冶金
生态学
机器学习
生物
计算机图形学(图像)
作者
Seán R. Kavanagh,Christopher N. Savory,Shanti Maria Liga,Gerasimos Konstantatos,Aron Walsh,David O. Scanlon
标识
DOI:10.1021/acs.jpclett.2c02436
摘要
Low-cost, nontoxic, and earth-abundant photovoltaic materials are long-sought targets in the solar cell research community. Perovskite-inspired materials have emerged as promising candidates for this goal, with researchers employing materials design strategies including structural, dimensional, and compositional transformations to avoid the use of rare and toxic elemental constituents, while attempting to maintain high optoelectronic performance. These strategies have recently been invoked to propose Ti-based vacancy-ordered halide perovskites (A2TiX6; A = CH3NH3, Cs, Rb, or K; X = I, Br, or Cl) for photovoltaic operation, following the initial promise of Cs2SnX6 compounds. Theoretical investigations of these materials, however, consistently overestimate their band gaps, a fundamental property for photovoltaic applications. Here, we reveal strong excitonic effects as the origin of this discrepancy between theory and experiment, a consequence of both low structural dimensionality and band localization. These findings have vital implications for the optoelectronic application of these compounds while also highlighting the importance of frontier-orbital character for chemical substitution in materials design strategies.
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